In this Mentored Clinical Scientist Development Award, a program of research and career development is proposed to investigate the development of environmental and neural controls of maternally-directed orienting and proximity-seeking behavior of newborn rats. Despite their importance for emotional and social development, little is known about the forms, ontogeny, and biology of the first behaviors by which infants seek closeness and contact with their mothers. The investigator and his colleagues have described an organized repertoire of maternally-directed orienting and proximity-seeking behaviors in the newborn laboratory rat: traveling, wedging, and wriggling under the mother's body, turning upside down under her ventrum, ventroflexing while upside down, and audible barking (Polan, Soo-Hoo, Hofer, 1997). These behaviors are expressed immediately after birth, but their controls shift, with the first experiences of nursing, from physiologically-regulated action patterns to graded responses to tactile, thermal, and olfactory features of the mother, and to maternal deprivation. These behaviors appear to be analogous to the emergence of the human infant's specific attachment to its mother. Tests of one candidate neuromodulator, dopamine, suggest that it mediates the behaviors' regulation by maternal features and deprivation. The research plan investigates the roles of the first experiences of nursing and behavioral interaction with the dam, and of birth itself in organizing the development of these behaviors, and, tests the role of dopamine as a mediator of the behaviors' motivational properties. The centerpiece of the education program is mentoring by four outstanding developmental psychobiologists, Drs. Myron Hofer, Gerard Smith, Gordon Barr, and William Smotherman from whom the candidate will learn specific new methods for the analysis of behavioral structure and mechanisms and the determination of their neural substrates. This program is both the critical next step in the candidate's transition to an independent investigator and a contribution to our understanding of the biobehavioral bases of mammalian filial behavior.